Year	Percent
1999	83.2
2001	84.4
2002	83.5
2003	83
2004	74.4
2005	68.7
2006	64
2007	57.1
2008	53.5
2009	62.1
2010	63.4
2011	60.8
2012	56.5
2013	54.6
2014	52.3
2015	48.3
2016	43.5